textproduct: Quad Cities

KEY MESSAGES

- Heavy rain and thunderstorms are likely for portions of the area tonight into Saturday morning and again Saturday evening into Saturday night. Localized flash flooding is the primary concern. Rapid rises on small creeks and streams and the flooding of low-lying areas are possible.

- A Flood Watch has been issued for portions of east-central Iowa and far northwestern Illinois for late tonight through Saturday evening. Rainfall totals of 1-3 inches are likely (60-80%) in these areas with the potential for localized areas of 3+ inches.

- There is a Marginal Risk for isolated severe storms for areas south of Highway 20 on Saturday. Primary severe hazard is damaging winds.

SHORT TERM /THROUGH SATURDAY NIGHT/

Issued at 245 PM CDT Fri Sep 18 2026

Tonight: Another round of heavy rain and thunderstorms is expected to develop across far north-central Iowa and southern Minnesota before shifting to the E/SE, likely impacting areas north of I-80 late tonight into early Saturday morning. This is a high confidence round of heavy rain forced by isentropic upglide, low-level convergence and an anomalously moist atmosphere with near record PWATs (~2").

The Flood Watch, which is in effect from late tonight through Saturday evening, has been expanded further the west and southwest by roughly a tier of counties remaining north/northeast of Cedar Rapids and the Quad Cities. Rainfall amounts between 1-3 inches are likely with localized areas of 3+ inches possible. The more widespread rainfall looks to come in two rounds: 1) Late tonight into early Saturday morning, 2) Saturday evening into Saturday night. There is a Moderate Risk (level 3 of 4) for flash flooding north of the I-80 corridor across far eastern Iowa and into northwest Illinois, with a Slight Risk (level 2 of 4) further to the west and south. Wet antecedent conditions, with a widespread 1-3"+ (locally higher) falling over the past several days along/north of the Highway 30 corridor, has made this area more susceptible to repeated rounds of heavy rain -- especially in urban areas or around steep terrain.

CAMs continue to highlight areas north/northeast of the Quad Cities with the highest QPF amounts, generally aligned with the current placement of the Flood Watch. The HREF and RRFS ensemble PMM QPF show potential for 1-3" swaths of rainfall with isolated pockets of 3-4" from late tonight through Saturday night.

There is also a Marginal Risk (level 1 of 5) for a few strong to severe storms later Saturday afternoon into Saturday night, with localized damaging winds as the primary threat.

LONG TERM /SUNDAY THROUGH FRIDAY/

Issued at 245 PM CDT Fri Sep 18 2026

Sunday...Occasional showers and isolated storms are possible through the day as an upper trough lingers over the region. Cooler temperatures are anticipated with highs in the 60s/70s accompanied by gusty northeast winds.

Sunday Night-Tuesday...The main trough over the Northern Rockies finally reaches the Northern Plains as low-to-mid-level ridging over south-central Canada continues to push the surface trough further south into the lower Ohio River Valley. Despite the cold air advection, CVA ahead of the trough keeps scattered light-to-moderate showers (50-70% coverage) around Sunday night into Monday. By Monday night, the trough finally reaches Iowa as cold-core showers form underneath, keeping PoPs around through Tuesday morning. As subsidence sets in on the backside of the trough and high pressure builds in from the north, the outlook area should be rain-free by Tuesday evening.

Wednesday-Thursday...Fall-like weather is likely (70-90%) to return for the middle of next week. Confluence aloft and surface high pressure is forecasted to keep Wednesday and Thursday dry as CAA keeps temperatures below average with highs in the mid-60s to low 70s and lows in the mid-40s to low 50s.

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/

Issued at 634 PM CDT Fri Sep 18 2026

Weak boundary from northern Iowa into central Illinois has weak convergence along it which may play into nocturnal convection. Main storm complex to move from Minnesota into Wisconsin with the southern part impacting as far south as Highway 30 after 12z/19. SHRA/TSRA expected with MVFR/IFR conditions widespread north of I-80. Nocturnal convection to dissipate after 15z/19 but left over boundaries to fire diurnal convection after 18z/19.

DVN WATCHES/WARNINGS/ADVISORIES

IA...Flood Watch from 1 AM CDT Saturday through Saturday evening for IAZ040>042-053-054-066. IL...Flood Watch from 1 AM CDT Saturday through Saturday evening for ILZ001-002-007-009. MO...None.